Sheet metal container



Aug. 25, 1970 w. *r. SAUNDERS SHEET METAL CONTAINER 2 Sheets-Sheet lFiled Aug.

FIGS,

v INVENTOR. WILLIAM T. SAUNDERS ATTORNEYS United States Patent 6;

3,525,455 Patented Aug. 25, 1970 Bee Int. Cl. B65d 7/42 US. Cl. 22067 12Claims This invention relates to improvements on sheet metal containersparticularly of the type in which an end cover is double seamed to thebody portion to close and seal the container.

"Conventional sheet metal containers, such as of the type in which foodand beverage products are marketed, include a body portion, which may beof cylindrical form, and end covers which are double seamed to the endsof the body member to close and seal the container. The central portionof the end cover is located inwardly with respect to the end of thecontainer and is surrounded by a vertical wall, referred to as thecountersink wall, which lies in close-fitting contact with the insideend surface of the body member. The end cover includes an outer portionextending from the countersink wall which is folded over and with anextension of the end wall of the body portion in a double seam whichprojects radially beyond the body portion and the double sea-m with thecountersink wall forming a relatively wide rim at the end of thecontainer. Containers of the foregoing type include inherent structuralweakness and, in order to prevent bulging of the end covers and failureof the container by outward buckling of the end cover, in the presenceof anticipated internal pressures, the end covers formed of heavy gagematerial of high tensile strength greatly in excess of the ultimatestrength of the material required merely to contain anticipated internalpressures and the end covers are formed to include a circumferentialreinforcing bead close to the countersink wall.

It is an object of the present invention to provide a novel sheet metalcontainer of the double seam type which overcomes the foregoingdisadvantages.

Another object is to provide a sheet metal container of the double seamtype in which the end covers are formed of relatively light platematerial and of lower tensile strength as compared to end covers ofdouble seamed sheet metal containers constructed according to the priorart.

Still another object of the present invention is to provide a novelsheet metal container of the double seam type which is capable ofcontaining high internal pressures without bulging of the end covers orfailure by outward buckling of the end covers yet permits the containerto be opened by piercing or cutting the end cover upon the applicationof a relatively small force as compared with the force required to openprior double seamed sheet metal containers.

A still further object is to provide a novel sheet metal container ofthe double seamed type having the foregoing characteristics in which endcovers are formed of relatively light plate material of lower tensilestrength as compared to the end covers of prior double seamed sheetmetal containers and which provides a properly sized rim at the end ofthe container to permit opening of the container by use of conventionalpiercing or cutting devices.

Other objects and features of the present invention will appear morefully from the following detailed description considered in connectionwith the accompanying drawings which disclose several embodiments of theinvention. It is to be expressly understood however that the drawingsare designed for purposes of illustration only and not as a definitionof the limits of the invention, reference for the latter purpose beinghad to the appended claims.

In the drawings, in which similar reference characters correspond tosimilar elements throughout the various views:

FIG. 1 is a three-dimensional view of an end of a double seamed sheetmetal container according to the prior art illustrating typical failureby outward buckling due to excessive internal pressure;

FIG. 2 is an enlarged view in section taken along the line 2-2 of FIG.1;

FIG. 3 is a top view in plan of a sheet metal container constructed inaccordance with the principles of the present invention;

FIG. 4 is a view in section taken along the line 4--4 of FIG. 3;

FIG. 5 is an enlarged view of one side of the structure shown in FIG. 4;

FIG. 6 is a view in section showing another embodiment of the presentinvention;

FIGS. 7, 8, 9 and 10 are views in section illustrating successive stepsin the forming of an end cover in accord ance with the presentinvention; and

FIG. 11 illustrates a cover member constructed in accordance with thepresent invention in position with a body member prior to the doubleseaming operation.

In FIGS. 1 and 2 of the drawings, there is shown a double seamed sheetmetal container constructed in accordance with the prior art including abody member 10, of cylindrical shape, and an end cover 11, the normalshape and position of the end cover 11 being shown in broken lines. Theend cover 11 includes a central portion 12 surrounded by a vertical orcountersink wall 13 which lies in contact with the inside surface of thebody member adjacent its end. The end cover also includes acircumferential reinforcing bead 14 adjacent the countersink wall and anouter portion 15 extending from the countersink wall which is rolledwith the end of the body member to form a double seam 16 which projectsradially from the body member. The double seam 16 and the countersinkwall 13 form a rim 17 at the end of the container.

When pressure exists within the container, there will be a tendency forpressurized gas to enter the interface between the countersink wall 13and the body member and, if the internal pressure exceeds therestraining force presented by the countersink wall 13 and the outerperiphery of the central portion 12, the countersink wall will be forcedaway from the body member at one region of its periphery and thecountersink wall will be deformed and pushed upwardly together with theadjacent outer peripheral part of the central portion, as viewed in thedrawing, to the position shown in FIG. 2 resulting in failure of thecontainer due to outward buckling of the end cover. As mentioned above,according to prior practice, end covers are formed of relatively heavyplate of high tensile strength and the reinforcing bead 14 is providedall for the purpose of preventing failures of the foregoing character inthe presence of anticipated internal pressures. Containers of the priorconstruction for marketing other carbonated beverages require end coversto be formed of heavy plate of the same order used for beer containersalthough a pasteurization process is not involved and although internalpressures due to extremely adverse storage conditions would probably notapproach a buckling pressure of about p.s.i.g. However, normal storageconditions for carbonated beverages develop internal pressures up to 70p.s.i.g. at which pressure the end covers bulge outwardly and it hasbeen determined that, in order to prevent outward bulging at the endcovers in the presence of internal pressures of about 70 p.s.i.g., it isnecessary that containers of the prior construction possess a bucklingpressure of the order of 95 p.s.i.g. The

necessity to form end covers of heavy plate is not only expensive butthe containers are difficult to open. In order to overcome thistendency, and also to prevent outward bulging of the end covers whensubject to anticipated internal pressures, it has been the practice inthe past to form the end covers of heavy plate of high tensile strengthand to provide the reinforcing bead 14 adjacent the countersink wall.

Prior to the present invention, double seamed sheet metal containers forbeer included end covers formed of heavy plate of from 90 to 107 poundsper base box providing a thickness of from 0.010 to 0.011 inch andpossessing a tensile strength up to 100,000 pounds per square inch inorder to contain the high internal pressures up to about 83 p.s.i.g.developed during the pasteurization process. In particular, a containerof the prior construction having end covers formed of 90 pounds per basebox double reduced renitrogenized plate having a tensile strength of100,000 pounds per square inch possesses a buckling pressure of about 95p.s.i.g. which is sufficiently above the cyclic internal pressuresdeveloped during the pasteurization process to safely permit the use ofsuch container for marketing of beer. Also, the use of heavy plate ofhigh tensile steel presents forming problems and decreases the life ofthe double seaming equipment.

As mentioned above, it is an object of the present invention to providea double seamed sheet metal container of novel construction whichpermits the end covers to be formed of light plate of low tensilestrength. The embodiment of the invention shown in FIGS. 3, 4 and 5 ofthe drawings comprises a sheet metal container including a body memberof cylindrical shape and a circular end cover 26 joined to an end of thebody member by a double searn 27 projecting radially beyond the bodymember; it is understood the other end of the container may be providedwith an end cover of similar construction. The end cover 26 includes acentral raised portion 28 merging into a depressed outer annular portion29 which is joined to a vertical countersink wall portion 30, thecountersink wall portion projecting longitudinally of the containerbeyond the central raised portion 28 to provide a recess for receiving achuck during the double seaming operation in accordance withconventional practice. The end cover 26 further includes an outerportion 31 extending from the countersink wall portion and terminatingin a cover hook 32 of the double seam 27 in double seamed relation witha body hook 33 formed at the end of the body member. In accordance withthe present invention, the material of the end cover 26 is of uniformthickness and improved resistance against outward bulging of the endcover and failure of the container by outward buckling of the end coveris obtained by forming the countersink wall portion 30 to include an oddnumber of folds of the end cover material greater than one, preferablythree folds. As shown in FIG. 5, the countersink wall includes an insidefold 35 extending from the annular portion 29 and overlying the innersurface 36 of the body member, and intermediate fold 37 extending fromthe outer end of the inner fold at shoulder 38 and overlying the innerfold 35, and an outer fold 39 extending from the inner end of theintermediate fold at shoulder 40 and overlying the intermediate fold andmerging into the outer portion 31. The folds 35, 37 and 39 are closelypressed together and form a countersink wall of a thickness a number oftimes greater than the thickness of the material forming the end coverequal to the number of folds and, as described below, the multifoldcountersink wall is formed in the end cover prior to joining and sealingthe end cover to the body member and the double seaming operation isperformed in a conventional manner.

The feature of merging the inner fold 35 from. the annular portion 29 ofthe end cover and of successively forming the remaining folds inwardlyof the container presents but one interface between the body member andthe countersink wall and inward lateral movement of the countersink walldue to the action of pressurized gas tending to enter the interface isresisted by a thickness of metal equal to three times the thickness ofthe material from which the end cover is formed. In addition, theimproved rigidity of the countersink wall resulting from at least threefolds resists deformation of the central portion of the end cover fromits normal position and prevents outward bulging of the end cover Whensubject to anticipated internal pressures notwithstanding the end coverbeing formed of light plate. Furthermore, the high rigidity of themulti-fold countersink wall makes it possible to form the end cover withthe central portion under tension to further increase the resistance tooutward bulging of the end cover.

As discussed above, the end cover of conventional double seamed sheetmetal containers, although formed of heavy plate of high tensilestrength, is provided with the reinforcing head 14, as shown in FIGS. 1and 2, to aid in resisting outward buckling of the end cover in thepresence of anticipated internal pressures. When practicing the presentinvention, such a reinforcing bead is unnecessary and, as shown in FIGS.4 and 5, the end cover includes a central raised portion or plateau 28and a depressed annular portion 29* merging with the inner fold of thecountersink wall. This feature is of particular importance with endcovers formed of light plate of 65 to pounds per base box which becomespracticable by the present invention since, with such light plate, therewould be a tendency of localized buckling in a reinforcing bead of thetype shown in FIGS. 1 and 2.

The embodiment of the invention shown in FIG. 6 of the drawings.includes a modified form of multi-fold countersink wall which increasesfurther resistance to outward buckling due to internal pressure. Asshown, the innermost end of the countersink wall tapers inwardly towardthe central longitudinal axis of the container and terminates in aconical portion 45. In this construction, the intermediate fold 37overlies at least the curved portion 46 of the end cover between theannular portion 29 and the inner fold 35, and the outer fold 39 issimilarly curved at its innermost end and overlies the intermediatefold. It will be appreciated that with this structure there is providedadditional metal resisting inward lateral movement of the inner fold 35.

End covers including a multi-fold countersink wall may be formed byrelatively simple die operations as shown in FIGS. 7, 8, 9, 10, and 11which are views in cross section of one side of the end cover duringvarious phases of its formation. FIG. 7 shows what may be referred to asthe starting blank 50 which may be formed by a simple pressingoperation. The blank 50 includes the central raised portion 28 and adouble seaming portion 51 joined by a slightly outwardly inclinedportion 52 and an inverted generally U-shaped portion 53. The first dieforming step is illustrated in FIG. 8 wherein the portion 52 is beingcollapsed outwardly beneath the portion 53 and the latter portion isbeing collapsed downwardly to initiate formation of folds .35, 37 and39. In FIG. 9, the folds are shown squeezed together and FIG. 10illustrates positioning of the squeezed folds to provide a countersinkwall in proper relationship with the other portions of the end cover asillustrated in FIG; 11. During the phase of FIG. 10, the central portion28 may be placed under tension, if desired. FIG. 11 also illustrates thebody member 25 terminating in a double seaming flange 55 and positionedrelative to the end cover prior to the double seaming operation.

As discussed above, conventional sheet metal containers for use inpacking beer include end covers formed of heavy plate of from to 107pounds per base box which are of thickness of 0.010 to 0.011 inch. Onthe other hand, by practicing the present invention, end covers for beercontainers may be formed of relatively light plate such as of from 70 to75 pounds per base box, which are of a thickness of 0.0076 to 0.0082inch providing a total countersink wall thickness of 0.0228 to 0.0246inch which is more than twice the thickness of the countersink wall ofprior double seamed sheet metal containers having end covers formed ofheavy plate of from 90 to 107 pounds per base box. As a further exampleof the advantages obtained by the present invention, a double seamedcontainer of prior construction including end covers of conventionalcontinuously annealed steel of 65 pound per base box plate was testedand found to fail by outward buckling under an internal pressure of 30to 35 p.s.i.g., while a container formed of the same material andconstructed according to the present invention possesses a bucklingpressure of greater than 70 p.s.i.g. Containers 'of the latter type aresuitable for and have been used to market carbonated beverages withoutbulging of the end covers although light plate is used to form the endscovers and the buckling pressure is less than what would be requiredwith the prior construction to present end cover bulging. Double seamedsheet metal containers constructed in accordance with the presentinvention with end covers constructed of conventional continuouslyannealed steel having a tensile strength of about 60,000 pounds persquare inch have been tested and found to possess a buckling pressure ofabout 92 p.s.i.g. when formed of 70 pound per base box plate and abuckling pressure of about 110 p.s.i.g. when formed of 75 pound per basebox plate, both with the requirements for beer containers. To illustratethe improvement obtained by the present invention, containersconstructed according to prior practices employing the same steel weretested and found to have a buckling pressure of 42 p.s.i.g. for 70 poundper base box plate and 49.5 p.s.i.g. for 75 pound per base box plate.

While the present invention has particular application to double seamedsheet metal containers used to market beer or carbonated beverages orother goods involving the existence of substantial internal pressures,the novel feature of a multi-fold countersink wall structure obtainsadditional advantages (Whether the container be pres- SUIlZBd or not.The formation of end covers of light plate from 75 pounds per base boxand below greatly decreases to an insignificant force the pressurerequired to open the container by pierce or wheel type openers. Theopening force surprisingly decreases at a rate substantially greaterthan the decrease in plate thickness and the ability to employ lightplate for end covers renders opening of the container a simple, painlesstask requiring insignificant effort. For example, end covers of priortype containers for beer and other carbonated beverages are required tobe formed from heavy plate of 90 pounds per base box or greater, and theforce required for plate of the latter weight is about 11 pounds. On theother hand, the opening force required for end covers formed from lightplate of 75 pounds per base box requires about 5 pounds, while about 4pounds is required to open end covers of 70 pounds per base box plateand about 4 pounds for end covers of 65 pounds per base box plate. Byway of contrast, the force required to open soft aluminum can ends bypunching is over 9 pounds and the force required to operate a tab-typeopener is over 7.5 pounds.

In addition to the foregoing, the principles of the present inventionmake it possible to employ in sheet metal containers light plateincluding light-weight tinplate in weights as low as 45 pounds per basebox. By way of example, containers for citrus juices could beadvantageously constructed of light plate; however, light platecontainers constructed according to the prior art are not acceptablesince the end rim possesses insufficient width to permit opening of thecontainer by conventional piercing or wheel type openers. Thisdisadvantage is overcome by the present invention as the three-foldcountersink wall provides an endrim. of suflicient width to enable thecontainer to readily open by employing conventional opening devices.

The present invention has particular application to sheet metalcontainers formed of tinplate which may or may not be lacquered but isalso applicable to containers formed of blackplate coated with organicmaterial or metal.

Although several embodiments of the invention have been disclosed anddescribed herein, it is to be expressly understood that various changesand substitutions may be made therein without departing from the spiritof the invention as well understood by those skilled in the art.Reference therefor will be had to the appended claims for a definitionof the limitations of the invention.

What is claimed is: 1. A sheet metal container comprising a body memberand an end cover joined to an end of the body member for closing andsealing the container,

the end cover including a central portion disposed inwardly from the endof the container at its close end,

the body member having an inside surface extending abount an axis of thecontainer with the inside surface including a portion between the planeof the central portion of the end cover and the plane of the closed endof the container parallel to said axis,

the end cover having its central portion surrounded by a wall portionand an outer portion secured to the end of the body member by a doubleseam which projects radially from the outside surface of the bodymember, the wall portion of the end cover being received within the bodymember in contact with the parallel portion of the inside surface of thebody member,

the end cover being formed of sheet metal material of uniform thickness,

the wall portion of the end cover comprising at least three overlappingfolds of said sheet metal material 'with adjacent surfaces of the foldsin mutual contact, and

the overlapping folds of the wall portion extending throughout a majorpart of the parallel portion of the inside surface of the body memberwith one of the folds in overlying contact therewith.

2. A sheet metal container as defined in claim 1 in which the fold inoverlapping contact with the parallel portion of the inner surface ofthe body member merges with the central portion of the end cover, and

in which the fold most removed from the parallel portion of the innersurface of the body member merges into the outer portion of the endcover.

3. A sheet metal container as defined in claim 1 in which theoverlapping folds comprise a first fold, a second fold and a third fold,

the first fold overlies the parallel portion of the inside surface ofthe body member and one edge of the tfirst fold merges with the centralportion of the end cover and the second edge of the first foldterminates in spaced relation with the central portion of the end cover.

the second fold overlies the first fold and one edge of the second foldmerges with the second edge of the first fold and the second edge of thesecond fold terminates adjacent the one edge of the first fold, and

the third fold overlies the second fold and one edge of the third foldmerges with the second edge of the second fold and the second edge ofthe third fold merges with the outer portion of the end cover.

4. A sheet metal container as defined in claim 3 in which the marginalportions of the first fold, the

second fold and the third fold adjacent the central portion of the endcover are curved downwardly toward the central portion of the end coverand inwardly toward the axis.

'5. A sheet metal container as defined in claim 3 in which the end coverincludes a depressed portion formed in the outer marginal regionthereof, and

in which the first fold merges with the depressed portion of the endcover.

6. A sheet metal container as defined in claim 5 in which the marginalportions of the second fold and the third fold adjacent the centralportion of the end cover are curved downwardly toward the centralportion of the end cover and inwardly toward the axis in overlyingrelation with the depressed portion.

7. A container having a tubular body having an end closure, said endclosure comprising a substantially fiat panel, a countersink wallextending upwardly therefrom and a flange portion extending outwardlyfrom said wall and joined in an end seam to said body, said countersinkwall consisting of an outer layer integral with and ex tending upwardlyfrom said panel, an intermediate layer integral with and extendingdownwardly from the top of said outer layer, said intermediate layerextending downwardly substantially to abutment with said panel, and aninner layer extending upwardly from the bottom of said intermediatelayer to said flange.

8. An end closure for a tubular container body comprising a flat centralpanel, a countersink wall extending upwardly therefrom and a flangeextending generally radially outwardly from said countersink wallwherein said countersink wall comprises an outer layer extendingupwardly from said panel, an intermediate layer integral with andextending downwardly from the top of said outer layer substantially tosaid panel and an inner layer integral with and extending upwardly fromthe bottom of said intermediate layer, said layers lying one against theother.

9. The end closure defined in claim 8 wherein said in- 8 termediatelayer extends downwardly and abutts against said panel.

10. The end closure defined in claim 9 wherein said flange extendsgenerally perpendicularly to said countersink wall.

11. The end closure defined in claim 10 wherein said countersink wall issubstantially perpendicular to said panel.

12. A container having a tubular body having an end closure, said endclosure comprising a substantially flat panel, a countersink Wallextending upwardly therefrom and a flange portion extending outwardlyfrom said wall and joined in an end seam to said body, said countersinkwall consisting of an outer layer integral with and extending upwardlyfrom said panel, an intermediate layer integral with and extendingdownwardly from the top of said outer layer, said intermediate layerextending downwardly to abutment with said panel, and an inner layerextending upwardly from the bottom of Said intermediate layer to saidflange.

References Cited UNITED STATES PATENTS 851,815 4/1907 Libbman 220-662,426,550 8/1947 Coyle 22067 2,894,844 7/1959 Shakman 220-66 3,186,5836/1965 Zundel 220-66 FOREIGN PATENTS 11,925 5/1903 Germany.

78,777 10/1918 Switzerland.

JOSEPH R. LECLAIR, Primary Examiner a J. R. GARRETT, Assistant ExaminerU.S. Cl. X.R.

PO-IObO (5/69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3|525o455 D d August 25, 1.970

William T. Saunders It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 31, after "covers" insert --are.

Column 5, line 21, change "present" to --prevent--.

Column 6, line 62, change the period to a comma oihiiib N KEALED rm 1 0(SEAL) Attest:

Edward M. Flewhwal I WILLIAM E. suaunm, JR. Amsting Commissioner ofPatents

1. A SHEET METAL CONTAINER COMPRISING A BODY MEMBER AND AN END COVERJOINED TO AN END OF THE BODY MEMBER FOR CLOSING AND SEALING THECONTAINER, THE END COVER INCLUDING A CENTRAL PORTION DISPOSED INWARDLYFROM THE END OF THE CONTAINER AT ITS CLOSED END, THE BODY MEMBER HAVINGAN INSIDE SURFACE EXTENDING ABOUNT AN AXIS OF THE CONTAINER WITH THEINSIDE SURFACE INCLUDING A PORTION BETWEEN THE PLANE OF THE CENTRALPORTION OF THE END COVER AND THE PLANE OF THE CLOSE END OF THE CONTAINERPARALLEL TO SAID AXIS, THE END COVER HAVING ITS CENTRAL PORTIONSURROUNDED BY A WALL PORTION AND AN OUTER PORTION SECURED TO THE END OFTHE BODY MEMBER BY A DOUBLE SEAM WHICH PROJECTS RADIALLY FROM THEOUTSIDE SURFACE OF THE BODY MEMBER, THE WALL PORTION OF THE END COVERBEING RECEIVED WITHIN THE BODY MEMBER IN CONTACT WITH THE PARALLELPORTION OF THE INSIDE SURFACE OF THE BODY MEMBER, THE END COVER BEINGFORMED OF SHEET METAL MATERIAL OF UNIFORM THICKNESS, THE WALL PORTION OFTHE END COVER COMPRISING AT LEAST THREE OVERLAPPING FOLDS OF SAID SHEETMETAL MATERIAL WITH ADJACENT SURFACES OF THE FOLDS IN MUTUAL CONTACT,AND THE OVERLAPPING FOLDS OF THE WALL PORTION EXTENDING THROUGHOUT AMAJOR PART OF THE PARALLEL PORTION OF THE INSIDE SURFACE OF THE BODYMEMBER WITH ONE OF THE FOLDS IN OVERLYING CONTACT THEREWITH.